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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 628 · 40 questions
TalentJR

The trick (Seventh times eleven): A leapfrog list: start with two numbers, then each number is the sum of the two before it, up to 10 numbers. Find the 7th number. Multiply it by 11 (the number with a 0 on the end, plus the number): that is the total of all 10.

NameDateTime takenScore ___ / 40
  1. 1.6 + 4 + 10 + 14 + 24 + 38 + 62 + 100 + 162 + 262 =
  2. 2.8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 + 474 =
  3. 3.Leapfrog list (each number is the sum of the two before it): 4, 8, 12, 20, 32, 52, 84, 136, 220, 356. What is 11 × the 7th number?
  4. 4.6 + 6 + 12 + 18 + 30 + 48 + 78 + 126 + 204 + 330 =
  5. 5.7 + 6 + 13 + 19 + 32 + 51 + 83 + 134 + 217 + 351 =
  6. 6.Leapfrog list (each number is the sum of the two before it): 3, 3, 6, 9, 15, 24, 39, 63, 102, 165. What is 11 × the 7th number?
  7. 7.4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 + 288 =
  8. 8.4 + 1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 =
  9. 9.Leapfrog list (each number is the sum of the two before it): 8, 9, 17, 26, 43, 69, 112, 181, 293, 474. What is 11 × the 7th number?
  10. 10.Leapfrog list (each number is the sum of the two before it): 7, 8, 15, 23, 38, 61, 99, 160, 259, 419. What is 11 × the 7th number?
  11. 11.A leapfrog list starts 8, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  12. 12.A leapfrog list starts 5, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  13. 13.A leapfrog list starts 8, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  14. 14.6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 + 432 =
  15. 15.5 + 1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 =
  16. 16.9 + 6 + 15 + 21 + 36 + 57 + 93 + 150 + 243 + 393 =
  17. 17.A leapfrog list starts 9, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  18. 18.A leapfrog list starts 2, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  19. 19.A leapfrog list starts 7, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  20. 20.Leapfrog list (each number is the sum of the two before it): 9, 8, 17, 25, 42, 67, 109, 176, 285, 461. What is 11 × the 7th number?
  21. 21.8 + 1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 =
  22. 22.Leapfrog list (each number is the sum of the two before it): 9, 2, 11, 13, 24, 37, 61, 98, 159, 257. What is 11 × the 7th number?
  23. 23.1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 =
  24. 24.A leapfrog list starts 1, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  25. 25.1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 =
  26. 26.8 + 6 + 14 + 20 + 34 + 54 + 88 + 142 + 230 + 372 =
  27. 27.Leapfrog list (each number is the sum of the two before it): 9, 5, 14, 19, 33, 52, 85, 137, 222, 359. What is 11 × the 7th number?
  28. 28.A leapfrog list starts 8, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  29. 29.A leapfrog list starts 2, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  30. 30.A leapfrog list starts 5, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  31. 31.A leapfrog list starts 8, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  32. 32.2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 + 314 =
  33. 33.A leapfrog list starts 1, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  34. 34.Leapfrog list (each number is the sum of the two before it): 9, 4, 13, 17, 30, 47, 77, 124, 201, 325. What is 11 × the 7th number?
  35. 35.A leapfrog list starts 4, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  36. 36.Leapfrog list (each number is the sum of the two before it): 3, 7, 10, 17, 27, 44, 71, 115, 186, 301. What is 11 × the 7th number?
  37. 37.Leapfrog list (each number is the sum of the two before it): 1, 8, 9, 17, 26, 43, 69, 112, 181, 293. What is 11 × the 7th number?
  38. 38.6 + 3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 =
  39. 39.Leapfrog list (each number is the sum of the two before it): 1, 1, 2, 3, 5, 8, 13, 21, 34, 55. What is 11 × the 7th number?
  40. 40.Leapfrog list (each number is the sum of the two before it): 1, 4, 5, 9, 14, 23, 37, 60, 97, 157. What is 11 × the 7th number?

Answer key

  1. 682
  2. 1232
  3. 924
  4. 858
  5. 913
  6. 429
  7. 748
  8. 308
  9. 1232
  10. 1089
  11. 880
  12. 363
  13. 528
  14. 1122
  15. 363
  16. 1023
  17. 1199
  18. 814
  19. 1001
  20. 1199
  21. 528
  22. 671
  23. 319
  24. 231
  25. 671
  26. 968
  27. 935
  28. 616
  29. 902
  30. 715
  31. 1056
  32. 814
  33. 847
  34. 847
  35. 924
  36. 781
  37. 759
  38. 594
  39. 143
  40. 407

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